Such plastic end disks have the task to provide a usually circular ring-shaped surface into which a filter medium can be embedded in a seal-tight way. Moreover, the plastic end disk should have a connecting contour that is suitable for producing a seal-tight and detachable connection to a connecting element. Such an end disk is disclosed in, for example, DE 199 19 289. Here, the manufacture of a plastic end disk is disclosed that is used for a seal-tight connection to a filter medium. For this purpose, stacked plastic disks are employed that have different thermal properties so that they can be selectively heated by inductive treatment.
DE 101 06 734 discloses a method for producing a connection between a fluid-impermeable plastic material and a fluid-permeable filter material. For this purpose, the plastic end disk is plastified in the area to be connected by an infrared heat source wherein the infrared heat source must have certain predetermined technical features.
A disadvantage of the first plastic end disk is that it must contain metal particles in order to be heatable by the inductive heat source because such plastic end disks are difficult to dispose of. The plastic end disk of the second method must not contain pigments for a colored or black design of the material which pigments have great heat-absorbing properties. This can cause in case of quick and intensive heating exothermal reactions within the synthetic material resulting in destruction of the material. Even without the heat-absorbing materials within the plastic material the radiation intensity that is acting on the plastic material must not be too great because this can cause bubble formation and burns on the surface of the plastic material.
It is an object of the invention to provide a plastic end disk that can be simply and inexpensively manufactured and that enables an especially homogenous plastification in the area of the joining zone at short plastification times. This object is solved in that the end face plastic layer is substantially transparent for infrared or heat radiation and a plastic layer neighboring it is configured so as to be substantially absorbent for infrared radiation. This object is further solved in regard to the method in that in a first step the first plastic layer that is substantially transparent for infrared radiation is trans-irradiated by an infrared radiation source, wherein the infrared radiation is absorbed in the second plastic layer that is substantially absorbent for infrared radiation and wherein a portion of the second plastic layer and the first plastic layer are completely melted, in a second step the infrared radiation source is removed, in a third step the terminal edges of the filter material are pressed into the still melted area of the first plastic layer, and in a forth step the pressed-in filter material is secured in the pressed-in position until a fixed connection has been formed with the synthetic material.